Absorption refrigerating apparatus



March 17, 1942. N. ERLAND AF KLEEN I l 2,276948 E ABSORPTIO REFRIGERATING APPARATUS Filed rJuly 2, 1940 '7'Sheetfs.-Sheet l THERMOSTAT BEL ,0 WS

INVENTOR.

wv ATTORNEY.

` March 17, 19152.Y N. l-:RLAND AF KLEEN 2,276,948

` ABSORPTION REFRIGERATING APPARATUS Filed July 2, 1940 7 sheets-sheet 2 v MATTORNEY.

March 17, 1942. l N. IERLAND AF KLEEN s 2,276,948

ABSORPTION REFRGERATING APPARATUS Filed July 2, 1940 l7 Sheets-Sheet 3 March 17, 1942. N. ERLAND 'jAF KLEEN 2,276,948'

ABSORPTION REFRGERATING APPARATUS Filed July 2, 1949 A 7 Sheets-Sheet 5- rjfla l ,HJ-C

March 17, 1942. N. ERLAND AF KLEEN 2,276,948

ABSORPTION REFRGERATING APPARATUS Filed July 2, 1940 vlsheets-s'heets.

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' I INVENTOR /W/r/Widaflfwz MATTORNEY.

March 17, 1942. N. ERLAND AF`KLEEN Y 2,276,948

ABSORPTION REFRIGERATING APPARATUS Filedv July 2, 1940 '7 Sheets-Sheet 7 l Y INVENTOR. MXN? [d Q1 w BY Ww ATTORNEY.

Patented Mar. 17,v 1942 UNITE-D STATES PATENT OFFICE ABSORPTION REFRIGERATING APPARATUS Nils Erland af Kleen, Stockholm, Sweden Application July 2, 1940, Serial No. 343,520

8 Claims.

This invention relates to absorptionrefrigerating systems of the kind comprisngtwo or more boiler absorbers arranged to work in cyclic order so as to maintain a substantially contin ucus refrigeration. Such systems usually have two boiler absorbers which work alternately so cycle, so that the heat stored in one boiler absorber at the end of its generating period is used to warm up the other boiler absorber in preparation for the generating period of the latter.

In the operation of a system of the kind described, the temperature of the boiler absorber rises to a maximum-at the end of theV generating period and its temperature must be rapidly lowered at the beginning of the absorbing period. At the beginning of the generating period, on the other hand, the boiler absorber requires to be heated up so that when two boiler absorbers are working alternately heat is required for raising the temperature of one boiler absorber at a time when the other boiler absorber requires to be cooled down from a high temperature. The heat from one boiler absorber just being in generating phase will, during its first cooling down period supply heat to the other boiler absorber to heatup the same to a point where the refrigerant starts to drive out.

The present invention takes advantage of these conditions by utilizing the heat of the boiler which ber associated 'with the second boiler absorben so that a closed circulating system is formed which may be lled with any suitable fluid capable of taking up heat from one boiler absorber and delivering the heat to the other boiler absorber.

',Thelheat-exchanging system can also consist of a separate circulating system.- The system ture of the boiler absorber which is being heatedup. The circulating iiuid may have a boiling point so adjusted that the fluid boils in the jacket or chamber associated with the hotter boiler absorber and condenses in the jacket or chamber associated with the cooler boilerv absorber` The circulating system may involve a reservoir or collecting chamber arranged to collect the condensed fluid at the end of the heat-exchanging period. I

1f desired a condenser or condensers may be interposed in the return pipe which connects the lower ends of the two jackets, so as to eiect condensation of the cooling iiuid on its way from the. warmer cooling' jacket to the colder one.

When a condenser or condensers is or are so arranged, the sensible heat of the` vapour delivered from the cooling jacket of the hot Vboiler absorber will be relied upon to warm the cold boiler absorber, and the' further loss of heat from the circulating fluid which occurs in the condenser or condensers, will increase the cooling effect of sorber is greater than the required rate of supmay be controlled by a valve cr valves operated automatically by thermostatic control mechanism arranged so that circulation is permitted during the initial cooling periodof one boiler absorber ply of heat -to the cool boiler absorber.

It is also possible to utilize the secondary cooling system provided for cooling the boiler ab i scrbers during their absorbing periods.` For this purpose, means may be provided for diverting the condensed cooling fluid which normally returns from the condenser of the secondary cooling system direct to the boiler absorber in process of being cooled, so that this iluid passes through the.

boiler absorber which is beingheated on its way from the condenser to the boiler absorber being absorber and cooling of the othervboiler absorber then proceeds in the normal mannner.

'I'he invention will be described in detail with reference to forms of construction of the same which are shown as examples in the accom panying drawings, inwhich Fig. 1 is a time-temperature-pressure diagram ,for a complete cycle of operation of the absorption refrigerating apparatus in accordance ,with the present invention;

Fig. 2 is a diagrammatic view of the refrigerating apparatus including two units` with certain parts shown in section and illustrating one form of mechanism for effecting a heat exchange between the cooling uid of the two units, the` parts of said mechanism occupying one of their fully closed positions:

Fig. 3 is a horizontal sectional detail of the mechanism illustrated in Fig. 2 with the parts occupying the other fully closed position;

Fig. 4 is a similar view, but showing the parts of the mechanism occupying an intermediate or. neutral position;

Fig. 5 is a horizontal sectional detail view of a modified form of mechanism with the parts occupying one of the fully closed positions;

Fig. 6 is a view similar to Fig. 5, but showing l the parts in an intermediate or neutral position;

central'portion of said partition is an opening through which projects the upper portion of switch lever 22 secured as at 23 to a flexible bellows diaphragm arrangement-24 adjacent the opening in the partition which forms a fulcrum for the switch lever 22. The upper end of the switch lever has a longitudinal slot 25 for receiving a transverse pin 26 on the valve rod I9 whereby movement of the switch lever is transmitted to the valve rod I3 to shift the same in the Valve chamber I1. The lower end of the lever 22 carries a contact member 21 connected to a suitable source of electric current and adapted to cooperate with a pair of ycomplementary contactmembers 28 and 28a secured' in the casing I8 and in electrical circuit with respective heat cartridges I3 and I3a. As lever 22 is rocked on its fulcrum 23, the contact member 21 will engage complementary contact 26 or 28a to close the circuit to the cartridge I3 or I3a and this rocking movement of the switch lever 22 is transmitted to the valve rod I9 to close the valve 2li or 20a upon its seat. Spring 29 secured unit on the left hand side of the drawing includes the usual boiler absorber I0 charged with absorbent material, condenser II, and evaporator I2, all connected together by suitable pipes or-conduits and forming a closed system or primary circuit for the refrigerant; the unit shown on the right hand side includes aboiler absorber I 0a, condenser IIa, and evaporator I2a, all connected together in series to form a similar closed system or primary circuit for the refrigerant."`The boiler absorbers III and Ilia are alternately heated for the expulsionphase op` eration of the units by any suitable means such a's electric heat cartridges I3 and I3a, respectively, controlled by a switch mechanism hereinafter described in detail.

For the absorption phase operation of each unit, the boiler Vabsorbers III and Ilia are alternately cooled by means of a cooling medium owing through a secondary system or circuit formed by the usualbciler absorber jackets Il and Ila, condensers I! and I5a,\common collecting-tank I6, and common valve chamber I1, all connected by pipe lines as shown in the drawings. The valve chamber I1 in this form of thev invention is located in the upper portion of a housing or casing I3. and interposed in the valve chamber and .reciprocable therein is .a valve rod I9 carrying a pair of valves 2.6`and 26a cooperating with respective valve seats inthe valve chamber for controlling the flow oi' the cooling to the .correspondingjboiler absorber' jackets I4 and Ila. A horizontal Ypartition 2| separates the valve chamberI1 fromthe lowerV portion of the casing I3, and substantially-lilium at one end of the casing I6 in the valve chamber I1 cooperates at its other end with the upper portion of the switch lever 22 to normally. urge the latter toward its extreme valve closing .positions.

The mechanism for selectively rocking the switch lever 22 comprises `a pair of pressurev absorbers I6 and liia,`respectively. The bellows diaphram 36 and 30a carry operating rods 32 and 32a, respectively, extending inwardly into the casingl I8 and terminating in contact faces 33 and 33a adapted to engage opposite sides of the lever 22 to selectively rock the latter to its extreme valve closing and corresponding heat cartridge energizing positions. A pair of levers 36 and 31 pivotally mounted in the lower portion of the casing I6 as at 34 and 36 extend upwardly in the casing and are normally maintained in engagement at their upper end with fixed abutments 38 andv 39, respectively, by springs 40 and Il. The levers 36 and 31 are provided adjacent their lower ends with arms 42 and I3 projecting inwardly toward one another and lying in the path of movement of the lower end oi' the switch lever 22 to prevent the latter from being rocked to its extreme positions as will hereinafter appear.4 Each lever 36 and 31 has a longitudinal slot 44 and l5, respectively, intermediate its ends -through which projects the free end of the voperating rods 32 and 32a, and adjacent said slots tranverse members 46 and a are pivotally secured to respective rods 32 and 32a to .move the corresponding levers 36 and 31 inwardly fromV their abutments 38 and 3l during the inward movement of the bellows diaphragme 3l and 36a.

Having described the construction of one form o! the invention its operation is as follows:

With the parts occupying the position shown in Fig. 2, the circuit to the heat cartridge Ila is closed and the boiler absorber Ila is being heated for the expulsion phase-(operation of the unit shown in the righthanclv side of Fig. `i?. During this heating the pressure in the system 3Ia will Asshown in Fig. 3,

gradually increase as shown in Fig. 1 by the heavy solid line b to correspondingly move the bellows diaphragm 30a towards its No. 3 position. On the other hand, the unit on the left is operating in the absorption phase; that is, the heat cartridge I3 is not energized and the valve 20 is-open to allow the cooling medium to circulate through the boiler absorber jacket I4 to cool boiler absorber I0. This will correspondingly cool the system 3l reducing the pressure as shown bythe heavy broken line a in Fig. 1 on the bellows eiects a considerable saving in applied heat and correspondingly increases the efficiency of the 30 so that the spring 40 acting upon lever 36 i returns bellows 30 toward its No. 1 position. v

The temperature in boiler absorber IB is indicated by dot and dash line c while the temperature in boiler absorber I Ila. is indicated by dot and dash line d in Fig. 1.

When the desired temperature has been reached in boiler absorber ita, the pressure in system 3 la has reached its upper operating limit as shown in Fig. 1. The bellows 30a has moved to its No. 3 position, and the switch lever 33 has been rocked by the contact face 33a on rod 32a to break the circuit to heat cartridge I 3a. Bellows 30 having returned to its No. 1 position due to the drop in pressure in the system 3|, the arm 42 on lever 36 has thus been brought into the path of the switch lever 32 to prevent the latter from being rocked by its spring 29 to its opposite extreme position. This vintermediate or neutral position of the switch lever 2,2 holds both valves and 20a open,

allowing the cooling iluid to circulate through.

both boiler absorber jackets' I4 and I 4a.

The circulation of theI cooling fluid from one boiler jacket to the other through the valve chamber l l eects a heat exchange between both I boiler absorbers to quickly cool boiler absorber Illa and gradually heat boiler `absorber III while both heat cartridges i3 and IIa are de-energized. In other words, in cooling boiler absorber 10a, the cooling fluid absorbs the heat therefrom and delivers it to boiler absorber I 0 to pre-heat the latter prior to operation of the heat cartridge I3. The switch lever 2'2 will remain in its intermediate or neutral position until the temperature in boiler absorber lDa falls below that in boiler absorber IB when bellows diaphra S@ has moved from its No. l position to im No. '2

in the opposite direction. In other words, the

switch lever 22 will first be moved toward the left by the bellows 3@ when the desired amount .oi heat has been attained for the boiler absorber IB.' shutting ofi' the current to the heat cartridge I3 and opening valve 38 without completely closing valve 28a, as illustrated in Fig. 4. The switch lever 22 will remain in this intermediate position until the temperature in boiler absorber ma has been raised a sumcient amount to actuate bellows 30a from its No. l position to its No. 3 position to disengage .the stop arm 43 i'rom'the lower end of the switch lever 22 to permit the latter to be rocked by the spring 29 to its extreme position completely closing valve 20a and energizing heat cartridge 43a as shown in Fig. 2. It will thus be seen that during the operation of the apparatus. the switch mechanism hereinabove described entire system inthat it enables a rapid cooling of the boiler absorber for the absorption phase operation thereof and at the same time enables the heat taken from the hot boiler absorber to initially raise the temperature in a second boiler absorber for the expulsion phase operation of the latter.

While in the foregoing form of the invention the switch lever is operated from an extreme position to anfintermediate .position by one bellows diaphragm and released from its intermediate position to its other extreme ppsition by the actionV of a second bellows diaphragm, the invention can also be used in connection with op.- positely disposed bellows wherein each bellows operates first to rock the switch lever from one extreme position to an intermediate position and then release the switch lever from its intermediate position to be rocked to its other extreme position.

Figs. 5, 6 and '7 show such an arrangement comprising a pair of bellows 4'I and 48, similar to bellows 30 and 30a heretofore described, disposed on opposite sides of a valve chamber 49 and responsive to pressures in separate fluid systems in thermal contact with respective boiler absorbers (not shown)- In the form illustrated valves 50 and' 50a on opposite ends of a valve rod 5I .are

disposed in the lower portion ot the chamber 49.'

The valve rod is operatively connected to the lower end of a valve operating lever 62 pivoted at 53 in the chamber 49. A second lever M-pivoted at 55 in the upper portion of the chamber and spaced axially from the pivoted lever 52 extends downwardly and is operatively connected at its lower end to the upper end of lever B2 by means of a coil spring 56 which normally urges both of said levers 52 and 54 toward one another.

Plunger rods 51 and 6B secured to bellows 41 and 48 respectively terminate at their tree ends in contact faces on each side oi the upper end of lever 54 to selectively rock the latter in opposite directions on the pivot 56 upon movement of the bellows 4.1 and 48. Intermediate the ends of the plunger rods 51 and 58 and extending downwardly therefrom is a pair' of legs 59 and 60, respectively, each of which terminates in an yinwardlyextending portion 6I and 62, respectively, carrying abutments 63 and 64 adapted to cooperate with the-upper end of valve operating lever 52.

In operation, referring rst to Fig. 5 wherein the valve 60a is closed and the bellows 4l and 4s are in their No. 1 positions, when the desired amount of heat has been obtained in the boiler absorber operating in the expulsion phase, the bellows se will nrst be moved to its No. 2 position, rocking lever 54 on its pivot b5 so that it lies substantially vertical in the chamber 49. Further movement of the bellows lil toward its No. 3 position will shift lever ell past the vertical position to the position shown in Fig.6. Spring 58 will then urge valve operating lever B toward its opposite valve closing position. However, abutment S4 on the arm S2 will engage the upper portion of valve `operating lever S2 to hold the latter in an intermediate position 4opening both valves 5B and 50a and permitting cooling fluid to circulate from one boilerto the other. As soon as -the temperature' in the boiler absorber in thermal contact with bellows 48 drops below thetemperature in the other boiler absorber, the bellows de will move back towards its'No.I 1 position,l as shown in Fig. 7, permitting the valve operating lever 52 to be rocked to its extreme valve closing position by the springV 58 to close valve 5lonitsseat.

The operation for the second period is the same, but `with bellows 41 operating lever 54 to that shown in Fig.l2, with the exception of the valve arrangement in the valve chamber operable by the switch lever 22a. In this modified form the valve assembly comprises a valve block 65' slidable horizontally in guides 56 in the valve chamber i'la. The valve block 55 canies at its upper end a pair of oppositely disposed valves 61, B8 cooperating with respective valve seats in the chamber Ila for controlling the circulation of the cooling fluid through branch lines 69 and 10 in the lines leading from the boiler absorber jackets I4 and |411, respectively, to the corresponding condensers I5 and I5a. A second pair of oppositely disposed valves 1| and 12 is-provided on the lower portion of the valve block B5 cooperating with valve seats for controlling the circulation of cooling fluid from the valve chamber Ila through the main lines leading to the boiler absorber jackets I4 and |4a. A valve member 13 on the upper end of the valve block 55 and slidable therewith controls the now of the cooling iiuid from the collecting tank I6 to the valve chamber I'Ia.

In operation, movement of the switch lever 22a from one of its extreme positions to its intermediate position by the switch lever 22a and operating mechanism previously described in connection with Fig. 2, opens the valves 1I 12 and closes valve 13 and the cooling fluid will circulate from one boiler absorber to the other as previously described in connection with Fig. 2. When the switch lever 22a is rocked to its extreme position, the valve 'I3 `will open and one set of valves 58E2 or 51 1| will remain open and the other set will be closed so that the -cooling medium will circulate only through the boiler absorber operating in the absorption phase.

Fig. 9 shows another embodiment of the-present invention wherein the circulation of the cooling medium can be selectively controlled by auxiliary bellows 14 and 15 responsive to the pressure in auxiliary fluid systems 16 and 16a in thermal contact with boiler absorbers I0 and Illa, respectively. These auxillarybellows 14 and 15 actuate valves v11 and 18 disposed in valve chambers 19 and l0 connected by branch lines 8| and 82 to the main lines ofthe cooling fluid of the secondary system. Branch lines 33 and I4 lead from the auxiliary valve chambers 15 and 5|! to the main valve chamber I1 containing the main valves 20 and 2||a`operable by the switch lever 22. The auxiliary bellows 14 and 15 operate mercury switches 50 Vand 9| -mounted on rocking levers 92 and 93 operatively connected to respective bellows 14 and 15 and movable therewith.

In this form of the invention, the mechanism heretofore described for maintaining the switch lever 22 inl an intermediate or neutral position is eliminated and the switch lever is free to move from one full operating position as shown in Fig.4 9 to the other full operating position by means of the operating rods 32 and 32a of bellows 3l and Ila, respectively. The auxiliary bellows 14 and 15 operate to maintain their respective valves 11 and 18 open until the'temperaturein the respective boiler absorbers AIl and Ila is ramd from the lower cooling temperature to that corresponding to the heat on" period shownin'Fig. 1.

When the auxiliary valves 11 and 1'8 are open. the mercury switches Il and 9| act to disconnect the circuit to the -respective heat cartridges I3 and |3a. Thus, the cooling viiuid can by-pass the closed main valve 2l or 20a to the corresponding absorber III ,is beginning to be cooled by the' A cooling medium. Contact 21 has been shifted to engage contact 28a in the circuit to the heat. cartridge |3a and valve 20a has been closed. However, the auxiliary bellows 15 holds valve 18 open to permit the cooling medium to by-pass valve 28 and circulate from boiler absorber jacket I4 to jacket I4a to pre-heat boiler absorber Ia. During this period the mercury switch 8| keeps the circuit to the heat cartridge I3a open so that the latter is not energized. Whe'n the temperature in boiler absorber Ia reaches a predetermined point, the pressure in auxiliary fluid system 16a increases to close auxiliary valve 18, rocking mercury switch 9| and closing the cir. cuit to the heat cartridge I3a. The parts will remain in this position until the desired amount oi heating has been obtained in. boiler absorber Illa when the fluid system 3Ia will operate bellows 30a to rock the switch lever 22 to the right, closing valve 20 and opening valve 2l, and shifting contact 21 into engagement with contact 28. The auxiliary bellows 14 and mercury switch 90 then operate in the manner above described in connection with bellows 15 and mercury switch 9|, to effect a heat exchange between boiler absorber Illa and boiler absorber I0 through the auxiliary valve 11, until boiler absorber Il has been pre-heated sulciently to permit auxiliary fluid 'I8 to close valve 11 and rock mercury switch i 50 for completing the circuit to the heat car-l tridge I3.

In the modiiication shown in Fig. 10. the boiler absorbers I0 and Ilia are cooled for the absorption phase operation of the units by two separate cooling systems. One of these systems is similar to that heretofore described and is formed by the inner boiler absorber jackets I4 and Ila, condensers Il and |5a, collecting tank I6, and valve chamber I1, all connected by pipe-lines as shown in the drawings. The boiler absorbers I0 and I0a are provided with an outer cooling' jacket |00 and Ina; respectively, connected together at their upper lends by a pipe-line and at their lower ends by pipe-lines leading to a,-

common-valve chamber |0| similar to valve chamber I1. Valves 2l vand 20a on valve rod I5 operate in valve chamber I1 to control the circulation of the cooling medium to the'respective boiler absorber jackets I4 and I4a, while valves |02 and |l2aeon valve rod |03 operate' in valve chamber Ill to control the circulation of the'cooling iiuid to the outer boiler absorber jackets Ill and IIIa. Both valve .rods I9 and |43 lare operated by a common switch lever |22 fulcrumed as at |23 toa bellows diaphragm arrangement' |24 in the -lower portion of valve chamber IM. The upper end of the switch lever A |2| carries a valve block 13a slidable in the valve chamber to control the flow of cooling medium from the collecting tank I6. The lower ilar numerals.

In operation, when the changing-over mechanism has rocked the switch lever |22 to a neutral position as heretofore described in connection with Fig. 2, both pairs of valves 20, 20a and |02, |02a. will be open'.v However, valve 13a will be moved to closed position so that only cooling uid circulating through the valve chamber and outer boiler absorber jackets |00 and |Il0a will be utilized to affect a heat exchange between the boiler absorbers l0 and Illa during the neutral position of the switch lever |22.

While in the foregoing description and inthe annexed claims, the expressions absorption and absorbent have been used, theyare intended to cover adsorption and adsorbent;" and the changing-over devices herein disclosed operate with equal efficiency in an adsorption refrigerating system.

From the foregoing it is believed that the operation and advantages of the present invention will be readily understood by those skilled inthe art without further description, it being borne in mind that numerous changes may be made tor coupled in series and forming a primary circuit for a refrigerant, separate heating 'means for said boiler absorbers for the expulsion phase operation of said units, control elements for connecting and disconnecting said heating means, means ,for cooling said boiler absorbers for the absorption phase operation of said units, and separate valve means for controlling' said cooling means to respective boiler chambers; mechanism for selectively controlling the operation of said units, comprising a movable. memberA operatively connected to said valve means and said control. elements, said member being. movable` to two extreme operating positionsrand a neutral position, movement of said member to one of said extreme operating positions connecting one of said heating means and closing one of said valve means, movement of said member to the other of said extreme operating positions' connecting the other'of said heating means vand closing th'e otherof said valve means, and movement of said member to said neutral position disconnecting both of said heating means and opening both oisaid valve means, whereby a heat exchange is eiectedbetween .said boiler absorbers through said cooling means, movable' ing part of the movement of said movable means.

in the details disclosed without departing from the spirit of the annexed claims.

What I claim is:

l. In absorption refrigerating apparatus of th'e class described including two units operating alternately and intermittently in the absorption and expulsion phases, respectively, each unit having a boiler absorber, means for heating the boiler absorber oi each unit for the expulsion phase operation thereof, means for cooling the boiler absorber of each unit for the absorption phase operation thereof, valve means for controlling said cooling means, a changing-over device movable between twoloperating positions for selectively connecting and disconnecting said heating means and respectively closing and opening said valve means to control the operation of said units from one ph'ase to the other, and separate elements responsive to the temperature of respective boiler absorbers for selectively actuatingy said changing-over device to its two operating positions; mechanism for eiecting heat exchange between said boiler absorbers during theoperation of said changing-over device, comprising a pair of members movable into and out of the path of movement of said changing-over device intermediate' the two operating .positions of the latter for respectively arresting and releasing said changing-over device during its movement from one operating position to the other, and means operatively connecting said members to sai-d temperature responsive elements for controlling the movement of said members.

2. In absorption reirigerating apparatus including at least two units operating alternately and intermittently in the absorption and expulsion phases, respectively, each' unit vhaving at least one boiler absorber containing solid absorbent material, a condenser, andan evapora- .3. In absorption refrigerating apparatus of the class described including two units operating alternately ,and intermittently in the absorption and expulsion phases, respectively,l each unit having a boiler absorber, means for heating the boiler absorber of each unit for the expulsion phase operation thereof, a plurality of elements including boilerv absorber jackets, condensers, collecting tank, and valve chamber, all coupled in series and forming a circulating system for a cooling medium to cool the boiler absorber of Aeach. unit for the absorption phase operation thereof, valve means in said valve chamber for controlling the circulation of said cooling medium to the respective boiler absorber jackets, control means for connectingl and disconnecting saidheating means, pivoted means'operatively connected to said valve means and control means and rokable between, two extreme positions for selectively actuating said valve means and, said control means, to change the operation of said units from one'phase to the other, a snap-spring device for normally maintaining said pivoted means in its respective extreme positions, and oppositely disposed pressure responsive means in thermal relation with respective boiler absorbers for selectively rocking said pivoted means from one extreme position to the other; mechanism for eiectingheat exchange between said boiler absorbers during a part of the operation of said units, comprising a pair of pivoted levers oper- I atively connected to respective pressure responsive means and movable therewith, and abutment members on said levers adjacent opposite sides of said pivoted means, adapted to engage the latter during partei the movement of said levers to maintain said pivoted means in an intermediate position, disconnecting said heating means and opening said valve means to allow circniation oi said cooling medium from one boiler absorber jacket to the other, further movement oi said levers by said pressure responsive means releasing said pivoted means,` whereby the latter is shifted to its full operating position by said spring device.

4:.r In absorption refrigerating apparatus of the class described and including two units operating alternately and intermittently in the absorption and explusion phases, respectively, each unit having a boiler absorber, separate electric heat cartridges for heating the boiler absorber of each unit in the expulsion phase operation thereof, a closed circulation system for a cooling medium to cool the boiler absorber of each unit for the absorption phase operation thereof, valve means in said system for selectively controlling the circulation of the cooling medium to respective boiler absorbers, and separate fluid pressure systems in thermal contact with respective boiler absorbers; a snap switch device for controlling the operation of said units from one phase to the other, comprising a rocking member operatively alternate phase relation to one another, each unit' having a boiler absorber,'means fory heating the boiler absorber of each unit with the expulsion phase operation thereof, and means for cooling the boiler absorber of each unit during the absorption phase operation thereof; the combination with a change-over device responsive to the temperature in each of said boiler absorbers and operable by the temperature in the boiler absorber of the unit operating in the expulsion connected to said heat cartridges and said valve means and movable between Atwo extreme positions for selectively actuating said heat cartridges and said valve means, one of said extreme positions energizing the heat cartridge on one boiler absorber and closing the valve means controlling circulation of the cooling medium to the second boiler absorber, and the other extreme position of said rocking member energizing the heat cartridge to the second boiler absorber and closing the valve means controlling circulation of the cooling medium to the rst boiler absorber, a pair of bellows diaphragm units cooperating with each side of said rocking member to move the latter alternately from one extreme position to the other and vice versa,4 spring means for urging said rocking member to its respective extreme position, and detent members operatively connected to respective bellows diaphragm units and movable thereby into the 'path of movement of said rocking member to hold the latter intermediate its extreme positions during part of the movement of said bellows diaphragm, disconnecting both of said heat cartridges and opening both of said valve means, whereby the cooling medium circulates from one boiler absorber to the other to effect a heat exchange between said boiler absorbers during a partof the operation of said umts, further movement of said bellows diaphragm units moving said detent members to release said rocking member.

5. In absorption refrigerating apparatus of the class described, including two units operating alternately and intermittently in the absorption and expulsion phases, respectively, a closed system for cooling medium to cool the units for the absorption phase operation thereof, valve means .for selectively controlling the circulation of said cooling medium to respective umts, means for vheating said units for the expulsion phase operation thereof, and a changing-over device operatively connected to said heating means and said valve means, responsive to the temperature in respective units and operable by the-temperature in the unit operating in the expulsion phase to change the operation of said units from one phase to the other; mechanism for eifecting heat exchange' between said units during part of the operation of said apparatus, comprising a pair of movable members cooperating with said changing-over device for disconnecting both oi said heating means and selectively controlling the circulation of cooling medium to both of said units, said movable members being responsive to the temperature in respective units and phase, for controlling the operation of said units from one phase to the other; of separate means responsive to the temperature in respective boiler absorbers, cooperating with said change-over device to render said heating means inactive to supply heat to said boiler absorbers during opera- 4tion of said change-over device, and to effect heat exchange between said boiler absorbers, whereby the heat from one boiler absorber is utilized to preheat the other prior to its being heated by said heating means.

'7. In absorption refrigerating apparatus of the intermittent type, the combination with two units operating in alternate phase relation to one another and each having a boiler absorber, means for heating the boiler absorber of each unit for theexpulsion phase operation thereof, a closed system for the circulation of a cooling medium to cool the boiler absorber of each unit during the absorption phase operation thereof, and valve means for selectively controlling the circulation of the cooling mediumto the respective boiler absorbers; of a change-over device, responsive to the temperature in each of said boiler absorbers, operatively connected to said heating means and said valve means and operable by the temperature in the boiler absorber of the unit operating in the expulsion phase, for controlling the operation of said units from one phase to the other, and separate means responsive to the temperature in respective boiler absorbers, cooperating vwith said change-over device to render saidheating means inactive to supply heat to said boiler absorbers during the operation of said changeover device, and to permit the circulation of said cooling medium from one boiler absorber to the other, whereby the heat taken up by the cooling medium from the hot boiler absorber is utilized to preheat the cold boiler absorber prior to its being heated by said heating means.

8. In absorption refrigerating apparatus of the intermittent type including at least two units operating in alternate phase relation to Ione another, each unit having a boiler absorber, means for heating ysaid boiler absorbers, a secondary cooling system for the circulation of a cooling medium in heat exchange relation with said boiler absorbers, and valve means for selectively controlling the circulation of the cooling medium -to said boiler absorbers; the combination with achange-over device, responsive to the temperature ineach of said boiler absorbers, operatively connected to 'said valve means and said heating means and movable from one operating position to another by the temperature in the boiler absorber Vof the unit operating in the expulsion phase, to control the operation or said units from permit the circulation of` the cooling medium v 'from one boiler absorber to the other, whereby the heat taken upvby said cooling medium from the hot boiler absorber is delivered to the cold boiler absorber to preheat the latter prior to its being heated by said heatingmeans.

NILs ERLAND n 

